Combination high- and low-pressure hydraulic pump



Jam. as, 1948. Q SWANSON 2,434,296

COMBINATION HIGH AND LOW PRESSURE HYDRAULIC PUMP Filed Feb. 19, 1945 ICARL T. SWANSON Patented Jan. 13, 1948 COMBINATION HIGH- ANDLOW-PRESSURE V HYDRAULIC PUMP c n '1'. Swanson, Quonset Point, 1;. 1.

Application February 19, 1945, Serial No. 578,757

3 Claims. (Cl. rot-s7) (Granted under the m or March 3, 1883, as

amended April 30, 1928: 370 0. G. 757) This invention relates to ahydraulic pump and hasfor an object to provide a hydraulic pump whichmay be used iorlsupplylng eitherlow or high pressure as maybe needed andwhich will automatically supply high pressure instead of low pressurewhen the high pressure is needed to overcome the resistance.'

. A further object of this: invention is to provide a hydraulic pumpwhich will supply low pressure until the resistance thereto becomes asgreat as the low pressure, whereupon the pump will automatically supplyhigh pressure.

Still a further object of this invention is to provide a pump that maybe manually operated for supplying fluid pressure, which pressure willshift automatically from low pressure to high pressure as the.resistance increases tosuch an amount that it may be only overcome byhigh pressure.

With the foregoing and other objects in view. the invention consists inthe construction, combination and arrangement of parts hereinafter setforth, claimed and illustrated in the drawing in which, the figure is apartly sectional, partly detailed, elevational view of the hydraulichigh and low pressure pump of this invention.

The hydraulic pump of this invention includes a main cylinder ii havinginlet and outlet valves i 2 and i3 connecting the main cylinder chamberIt by way of a passage I6 from an inlet fluid line I3 to an outletpressure line ll. Threaded on the cylinder H is a cylinder cap i3 onwhich is mounted a flange plate 20 acting as a base for 8. lug 2i towhich is pivoted a link 22, which link 22 in turn is pivoted at 23 to apump arm 24 terminating in a pump handle 25.

Also pivoted to the pump arm 24 as at 26 is a second link 21 which isinternally threaded for receiving the upper end of a piston rod 28. Thepiston rod extends through a bronze bushing 30 in the 'flange plate 20and cylinder cap l8 into the main cylinder H. Movable within thechammain piston 3|, the upper end of chamber 34 being closed by a nut 35threaded into the end of chamber 34. The connecting rod 28 is providedwith a circumferential ridge 38 within the chamber 34.

tends through a'cylindrical chamber 38 formed;

in the main cylinder 3i and the piston rod end 31 is provided with apacking ring cooperating with the walls of the cylindrical chamber 38.The nut 36 is provided with a small vent 4| permitting the nut 35 to beassembled in position. A larger vent 42 is provided through the flangedplate 20 and cap i3 to the topof main cylinder l i thereby permittingthe main piston 3i to move in the main chamber i4 .without'compressingany air .thereabove.

In operation, when the pump rod 24 is moved up and down manually bymeans of the pump handle 25, the double pivoted link 22 permits astraight vertical motion to be imparted to the connecting rod 28 and themain cylinder 3|. Due to the coil spring 33, the connecting rod 28transmits its motion to the main piston 3i pumping the fluid from theinlet line it and through inlet valve i 2 to the outlet valve i 3 andoutlet pressure line H until the resistance in the line I! becomes toogreat to continuemoving the main cylinder 3i up and down within its"chamber M in the main cylinder II and the operator then merely raisesthe handle 25 somewhat higher, thereupon com-. pressing spring 33 andmoving the end 31 of connecting rod 28 toward the top of cylindricalchamber 38, the vertical movement being limited by the piston rod ridge38 abutting the completely compressed spring. He then reverses hismotion to a down stroke, the coil spring 33 assisting in this downstroke. The ring packing causes the end 3'! of connecting rod 28 to actas a piston within the cylindrical chamber 38 and due to the smallcross-section of the cylindrical chamber 38 and piston rod end 31,considerably higher pressure will be created by this motion than it ispos- The lower end31 or the connecting rod 23 exsible-to create by themotion of the main piston 3i. it being noted that the cross-sectionalarea of the cylindrical chamber 38 is approximately one-fourth that ofthe cross-section area of themain cylinder chamber i4. 1 Obviouslyspring 33 could be omitted, and the back pressure alone could be reliedon to'hold piston 3| at the top of the cylinder while high pressure isbeing supplied. As a result thereof the operator first creates a lowpressure in the main chamber i4. until the back pressure from pressureline H becomes too great, whereupon. by merely raising the pump handlesomewhat higher the pump is automatically converted into a high pressurepump as he operates the piston-like end 31 of connecting rod 28' in thesmaller cylindrical chamber 38, thus continuing the pumping at a muchhigher pressure against the resistance in the pressure line i'l.

' memos der having fluid inlet and pressure outlet ports adjacent oneend thereof, a pumping piston reciprocable within said main pumpcylinder, a counterbored chamber extending through said piston with thesmall bore end toward said ports, a connecting rod reciprocablyextending through said counterbored piston, one end of said connectingrod forming a, pumping piston within the small bore of said counterboredchamber, means on said connecting rod within the large bore of saidcounterbored chamber yieldably securing said connecting rod to saidpiston, said yieldable securing means comprising a coil spring embracingsaid connecting rod, an abutment on said connecting rod within the largebore of said piston limiting the movement of said rod through the smallbore of said piston, one end of said spring being based on saidabutment, an apertured closure member for the other end said smallpiston rod chamber when said yielding means is compressed, whereby saidpump may deliver low pressure when said main cylinder piston isreciprocated and may deliver high pressure when said main piston abutsone end 0! its cylinder while said connecting rod is reciprocated withinsaid small chamber in said piston rod against said yieldable connectingmeans.

3. A combination low pressure high pressure hydraulic pump comprising amain pump cylinder having fluid inlet and pressure outlet ports, a mainpump'piston movable within said main cylinder, a pump arm, a linkpivctally connecting said pump arm relative to said main cylinder, aconnecting rod connected to said pump arm, a small cylindrical chamberin said main piston, an end of said piston rod extending into said smallpiston rod chamber, yieldabl means securing said connecting rod to saidpiston, said yieldable securing means comprising a coil spring embracingsaid connecting rod within a large cylindrical chamber therein, anabutment on said connecting rod within th large cylindrical chamber ofsaid piston limiting the movement of said of said large bore, the otherend of said spring being based on said closure member, the other end ofsaid connecting rod extending through said apertured closure member inthe end of the large bore in said piston and the end of said main .aconnecting rod connected to said pump arm, a

small cylindrical chamber in said main piston, an end of said piston rodextending into said small piston rod chamber, yieldable means securingsaid connecting rod to said piston, said yieldable securing meanscomprising a coil spring embracing said connecting rod within a largecylindrical chamber therein, an abutment on said connecting rod withinthe large cylindrical chamber of said piston limiting the movement ofsaid rod through the small cylindrical chamber of said piston, one endof said spring being based on said abutment, an apertured closure memberfor the other end of said large cylindrical chamber, the other end ofsaid spring being based on said closure member, said yieldable meanspermitting said piston rod end to reciprocate within rod through thesmall cylindrical chamber of said piston, one end of said spring beingbased on said abutment, an apertured closure member for the other end ofsaid large cylindrical chamber, the other end of said spring being basedon said closure member. said yieldable means permitting said piston rodnd to reciprocate within said small piston rod chamber when saidyielding means is compressed, whereby said pump may deliver low pressurewhen said main cylinder piston is re'ciprocated and may deliver highpressure when said main piston abuts one end of its cylinder while saidconnectingrod is reciprocated within saidlsmall chamber in said pistonrod against said yieldable connecting means, said main piston having apacking preventing leakage between said piston and the wall of said maincylinder, said piston-like end of said connect-l. ing rod within saidsmall piston chamber being provided with a packing to prevent leakagetherethrough.

CARL T. SWANSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 28,090, Lindsay May 1, 1860209,086 Stucky Oct. 15, 1878 1,047,007 Drugan Dec. 10, 1912 1,680,536Gensmer Aug. 14, 1928 1,794,356 Baker Mar. 3, 1931 2,083,854 McGee June15, 1937 FOREIGN PATENTS Number Country Date 3,503 Great Britain 1885

